Jimm is free software. Jimm is distributed under GNU General Public License v2 with full sources. By downloading Jimm, you agree to the terms and conditions of the GNU General Public License v2. You can find text of GNU General Public License v2 here: http://www.gnu.org/licenses/old-licenses/gpl-2.0.html.
Jimm sources are in public access at SVN repository:
You can find info about how to get sources from SVN repository here: http://sourceforge.net/svn/?group_id=100937. You have to use SVN client to access Jimm SVN repository. Read this for more info: http://subversion.tigris.org/.
If you don't want to use SVN client, you may browse Jimm sources by your web-browser here.
Also you can download archive with current Jimm sources from http://jimm.svn.sourceforge.net/viewvc/jimm/trunk.tar.gz?view=tar. For extraction sources from archive you can use 7zip archiver: http://www.7-zip.org/